1. Field of the Invention
The present invention relates to an optical disk reproducing device for outputting analog audio signals of two channels obtained by performing a prescribed process to audio information and a digital audio signal based on the audio information by using an RCA pin jack. More particularly, the present invention relates to an optical disk reproducing device for setting an outputted audio to a kind corresponding to the state of a connection of an RCA pin jack and an adapter for a plug usable for the optical disk reproducing device.
2. Description of the Related Art
In a DVD widely spread nowadays, kinds of reproduced audio can be switched to a Dolby Digital 2 ch (refer it simply to as a 2 ch, hereinafter), a Dolby Digital 5.1 ch (refer it simply to as a 5.1 ch, hereinafter) or a DTS (Digital Theater System) 5.1 ch. However, even when the 2 ch, the 5.1 ch or the DTS 5.1 ch is displayed on a setting screen, most of users hardly correctly understand the meaning of the display. Further, when the audio output of the 2 ch and the output of a video signal of a DVD player are connected to a television receiver, however, a digital audio output is not connected to a device capable of outputting the 5.1 ch, even if the 5.1 ch is selected, the audio of two channels of the 5.1 ch is merely outputted from the television receiver (most of the users do not notice it).
In order to overcome the above-described circumstances, a below-described technique is proposed (refer it to as a first related art). In this technique, six amplifiers provided for outputting the audio of the 5.1 ch are respectively provided with electric current detecting parts for detecting entering electric current. Then, for the amplifiers respectively, it is examined from the detected results of the electric current detecting parts when audio signals whose frequencies are swept are supplied to the amplifiers, whether or not a speaker is connected respectively to the amplifiers, or whether or not the speaker is a speaker for a low-pitched tone when the speaker is connected respectively to the amplifiers. Then, in accordance with the state of the speaker connected to the amplifiers respectively, a kind (a pattern of a reproduced form) of an optimum audio output is automatically selected and the kind of the selected audio is displayed on a display part. Further, a signal processing circuit is automatically set so that the kind of an audio signal outputted by the signal processing circuit corresponds to the kind of the selected audio signal. Further, this technique also discloses that a function is provided for displaying a kind of an audio output that can be selected by a user in accordance with the state of the speaker connected respectively to the amplifiers without the automatic selection (for instance, see JP-A-2003-204600).
Further, a below-described technique is proposed (refer it to as a second related art). In this technique, the connecting state of a cable of a 4-channel audio output terminal to which an audio connecting cable is connected is detected by using an output terminal connection detecting part. Then, an audio signal transmitted to the audio output terminal is switched to a signal of an optimum mode in accordance with the detected result (for instance, see JP-A-8-111900).
A below-described technique is proposed by the applicant of this application of the present invention (refer it to as a third related art). In this technique, a speaker unit and an RCA pin plug are provided in an accessory speaker. The RCA pin plug is electrically connected to the speaker unit. In a television receiver side, an RCA pin jack is provided and an audio signal is guided to the RCA pin jack. In an interior side of the RCA pin jack, a switch is provided that is pressed by an end part of the RCA pin plug so that its connecting state is switched. In the connecting state when the switch is not pressed by the RCA pin plug, the accessory speaker is not connected to the switch so that a stereo audio is outputted by two incorporated speakers provided in the television receiver. On the other hand, in the connecting state when the switch is pressed by the RCA pin plug, the accessory speaker is connected to the switch so that a stereo audio is outputted from a pair of right and left accessory speakers and a mono-ral audio obtained by adding the stereo audio signal is outputted from the two incorporated speakers. That is, when the accessory speaker is connected to the television receiver, the speakers incorporated in the television receiver are used as pseudo center speakers to obtain a surrounding effect (for instance, see JP-A-2004-282395).